Multi-Band Tracker Circuit With Shunt Filtering for Low RF Distortion
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Solution Overview
Problem
Existing power amplifier technologies using envelope tracking modes with discrete voltages often result in increased distortion of radio frequency signals, leading to spurious emissions and degradation of adjacent channel power ratio/adjacent channel leakage ratio (ACPR/ACLR).
Innovation Solution
A tracker circuit and method that include an output switching circuit, multiple voltage supply paths, and a filter circuit. The circuit selectively outputs discrete voltages to power amplifiers for different radio frequency bands and connects the filter circuit in shunt with the voltage supply paths based on the channel bandwidth of the radio frequency signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If discrete voltages are supplied to power amplifiers using envelope tracking modes, then power-added efficiency is improved, but distortion of radio frequency signals increases
Solution Approach 1:
The voltage supply is segmented into multiple discrete voltage levels that can be selectively applied to different power amplifiers based on signal requirements. The output switching circuit divides the voltage supply into separate paths, allowing each amplifier to receive appropriate voltage levels for its specific operating conditions, thereby maintaining efficiency while reducing distortion through optimized voltage selection
Solution Approach 2:
A filter circuit is introduced as an intermediary component between the voltage supply and the power amplifiers. This filter circuit selectively attenuates high-frequency components in the voltage supply that would otherwise cause distortion in the amplified RF signals. The filter acts as a mediator that allows the discrete voltage tracking to maintain efficiency while blocking the harmful high-frequency noise that causes distortion
2Object-generated harmful factors
If filter circuits are connected to voltage supply paths for all power amplifiers, then signal distortion is reduced, but tracker circuit size increases
Solution Approach 1:
The filter circuit connection is made dynamic rather than static. The output switching circuit selectively connects the filter circuit to specific voltage supply paths based on real-time operating conditions, such as which power amplifier is active and the characteristics of the RF signal being amplified. This dynamic connection allows the system to use filter protection only when needed, reducing overall circuit size while maintaining signal quality when required
Solution Approach 2:
Instead of applying filter circuits uniformly to all voltage supply paths, the system applies filtering selectively to specific paths based on local requirements. Each power amplifier's voltage supply path can independently have the filter connected or disconnected depending on its specific operating conditions, allowing optimized signal quality where needed while minimizing overall circuit complexity and size
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution reduces distortion of radio frequency signals amplified using discrete voltages, thereby minimizing spurious emissions and improving ACPR/ACLR, while also reducing the size of the tracker circuit.
Implementation Method 1
a first filter circuit that is connectable in shunt with the first voltage supply path and the second voltage supply path
Data Source
Figure 1A~1C
Figure 2
Figure 3
AI summary
A tracker circuit (1A) includes an output switching circuit (30), a voltage supply path (P41), a voltage supply path (P42), and a filter circuit (40A). The output switching circuit (30) is configured to selectively output at least one of a plurality of discrete voltages to power amplifiers (2A and 2B). The power amplifier (2A) is configured to amplify a radio frequency signal (RFA) of Band (A). The power amplifier (2B) is configured to amplify a radio frequency signal (RFB) of Band (B). The voltage supply path (P41) connects the output switching circuit (30) and the power amplifier (2A). The voltage supply path (P42) connects the output switching circuit (30) and the power amplifier (2B). The filter circuit (40A) is connectable in shunt with the voltage supply paths (P41 and P42).